This invention relates generally to silk screen printing apparatus of the type used to form serigraphs and more particularly concerns the provision of means for establishing automatic registration of the image receiving paper web on the printing cylinder to enable repeated passes of the same impressions successively to form multicolored serigraphs in proper registration.
The serigraphic art of printing involves the preparation of color separated silk screens carrying images to be applied to paper web or sheet material. A multitone or multicolor original work of art is utilized prepare a series of silk screens each containing one color separated image. All colors are separated to provide one screen for each represented color. Prints are made by impressing the particular colored ink through the screen using suitable application techniques to a continuous web of sheet material, usually paper. A limited number of impressions are serially made. Thereafter, the web carrying the first series of impressions is rewound, the second color separated screen substituted for the first and the second image is applied in registration with the first image until the series is completed. This process is repeated for as many colors as required to provide the multicolor serigraph print.
Considerable difficulty has heretofore been encountered in achievement of color registration in the course of making serigraphic prints. While color registration devices, web guide means, and similar adjustment means are well known in the printing art, particularly related to the high speed printing arts, none have been suitable for use to achieve proper registration in the serigraphic printing art. There are web guide problems, slippage and looping problems, successive rewinding and back tracking contribute to errors in registration in the serial process. Where there is a high speed run, waste is possible until the alignment is corrected. Moreover, the colors are serially successively applied inn a continuous stream process. In the serigraphic art, every print counts and complete rewinding and after a run with one color is required for application of the second color, and on with as many as twenty different colors all requiring complete rewind and proper registration during the next run. Ordinarily the process of serigraphic print making is a hand operated art not conducive to automation. Thus it would be highly advantageous to provide means whereby registration can be achieved automatically in the formation of serigraphic prints.